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Although you will technically be selling your ne third share of the Freehold, the other 2 Freeholders need to consent, in that your Buyers Solicitors will want to make sure that their client is registered at the Land Registry as owning the Freehold (one third share). This can only be done by a Transfer document being drawn up and signed by all 3 current Freeholders. Hence the other 2 Freeholders will need to sign this document, before your Buyer's Solicitor will be happy to proceed.
They should not have any real objection to this, as the same will need to happen as and when they sell their respective property.
I hope this assists and sets out the legal position.
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